Sorting apparatus



1954 R. E. MATTHEWS, JR

SORTING APPARATUS 6 Sheets-Sheet 1 Filed March 17, 1949 INVEN 0R. RALPH E. MA TTHEWS JR.

ATTORNEYS Dec. 7, 1954 R. E. MATTHEWS, JR

SORTING APPARATUS 6 Sheets-Sheet 2 Filed March 17 1949 YN 68k Pl m 8 9 M M s v INVENTOR. RALPH [.MATTHEWS JR.

ATTORNEYS D 7, 1954 R. E. MATTHEWS, JR 2,696,297

SORTING APPARATUS Filed March 17, 1949 6 Sheet s-Sheet s FIG. 2B.

INVENTOR. RALPH E.'MAT7'HEW$ JR By mix;

ATTORNEYS Dec. 7, 1954 R. E. MATTHEWS, JR

SORTING APPARATUS Filed March 17, .1949

6 Sheets-Sheet 4 INVENTOR. RALPH E. MA T THEWS JR.

ATTORNEYS Dec. 7, 1954 R. E. MATTHEWS, JR 2,696,297

SORTING APPARATUS Filed March 17, 1949 6 Sheets-Sheet 5 INVENTOR. RALPH E,MAT7'HEW$ JR.

i l iii} n H H H u s 1.

AllORNElS Dec. 7, 1954 R. E. MATTHEWS, JR

SORTING APPARATUS 6 Sheets-Sheet 6 Filed March 17, 1949 Q Q INVENTOR. RALPH E. MA TTHEWS JR ATTORNEYS United States Patent SORTING APPARATUS Ralph E. Matthews, In, Philadelphia, Pa., assig'nor, by

mesne assignments, to William S. Scull 2nd, Lansdale, Pa.

Application March 17, 1949', Serial N 0. 81,947

6 Claims. (Cl. 209'111) This invention relates to a sorting or similar apparatus particularly designed for the automatic electrical sorting, inspection or control of beans, nuts, fruits, etc.

Various types of sorting apparatus have been developed which, by photoelectric examination of the articles being sorted, segregate acceptable from unacceptable ones or etiect grading of various types. The types of apparatus provided for this purpose have generally involved the use of conveyors for carrying the articles to be sorted past a station at which the articles are examinedby photoelectric means. The use of conveyors necessarily slows down the rate at which sorting can be accomplished.

One of the objects of the present invention is the provision of a sorting apparatus capable of operating at high speed so as to provide a high rate of throughput of the articles to be sorted. In accordance with the invention the articles, when they pass the photoelectric scanning apparatus, are moving in free condition except possibly to the extent that they may be in contact with the wall of a guiding tube or similar conduit. At any rate, they are not necessarily equally spaced from each other as they pass the scanning station. In a preferred form of the invention they are, in fact, carried by an air stream at high velocity past the scanning station.

in view of the foregoing it is necessary to provide a selecting means which is capable of very high speed operation and a further object of the invention relates to the provision of such a selecting means and its controlling electrical circuit. In brief, this is provided by a light vane operated by a loud-speaker type of driver responsive to an electrical circuit which will insure positioning of the vane to effect the proper selection at the proper time- Another object of the invention is the provision of an improved circuit arrangement which utilizes the high sensitivity of one or more multiplier photocells to. effect color selection These and other objects. of the present invention having' to. do with structural details and the provision of proper feeding means, adjustments or replacements for the sorting oi different objects and the like will become apparent from the following description read inconjunction with the accompanying drawings in which:

Figure 1A is a side. elevation of one form of the preferred apparatus;

Figure 1B is a side elevation, partly in section, providing a continuation of the right hand end of Figure 1A;

Figures 2A and 2B are plan views, partly sectioned, which respectively illustrate the left and right hand portions of the apparatus;

Figure 3 is a section taken on the: broken surface indicated at 3-3 in Figure 1A;

Figure 4 .is a transverse section illustrating particular the disposition of various elements of a scanning system;

Figure 5 is a section takenon the broken surface in-- base carries. suitable structural elements supporting a 64 in Figure 5-.

"ice

hopper 4 for the reception of the articles to be sorted-v The particular apparatus illustratedis designed tor the sorting of beans or nuts such as coffee beans or peanuts and, in fact, it will be described with particular reference to the sorting of these. It will be evident, however, that minor changes of dimensions it may be modified for the purpose of sorting fresh or dried fruits, other types of nuts and beans, seeds, or many other articles. It may be assumed for uniformity of description that peanuts are being sorted with the understanding that the term peanut is used herein to describe the peanut seed with the husk removed.

The hopper 4 delivers the peanuts to a conventional feeder trough 6 which is vibrated by means of a conventio-na-l vibrator indicated at 8. The trough 6 is slightly sloping downwardly toward the right in Figure 1A so that the peanuts drop from its right hand end into a sloping guide structure generally indicated at 10 which is formed of sheet metal bent as indicated in Figure 3 to provide a plurality, in the present case three, of separate guideways' indicated at 12, each of the guideways in transverse cross-section having one vertical wall and one sloping' wall to provide a V-shaped channel. It has been found that this type of guideway is very effective in insuring that the peanuts approach the lower end of the guideway in single file so as to be presented singly in the spaces provided between horizontal extensions 13 of the vertical guide walls and the sides of a converging receiver generally indicated at 14 which is provided with a cover plate and is continued in the form of a tube 34.

A header 16. supplied with compressed air feeds, through a tube 18', a valve assembly comprising a stationary casing and a rotary valve element which is provided with a bore 2t) into which the incoming air flows. The valve element is provided with three sets of radial bores, each of which sets comprises three bores having their axes angul'arly spaced apart. The internal bore '24 of the valve casing is provided with ports 26, one being in the axial plane of each of the sets of bores 22, these ports being space-d 40 apart in an angular sense. Tubes 28 communicate with these ports and terminate at the rear ends of the spaces provided between. partitions 13' and the walls of the chamber 34.

The rotary valve element is driven through a. belt 30 by a motor 32 which may include suitable reduction gearing. to secure the desired rate of rotation of. the valve element. It will be evident from what has been described that pulses of air will be emitted from. the tubes 28 in sequence there being a total of nine pulses, three from. each tube during each revolution of the valve element. These pulses of air introduced behind the peanuts will project the peanuts at high. velocity through the tubular end of the chamber 34 and. through the transparent tubes 34'" and 34", the former of which is coupled to said tubular. end to form a. continuation thereof. The photoelectric scanning system indicated generally at 36 surrounds. adjacent ends of the transparent tubes 34- and 34".. This will be further. described hereafter.

At one side of the right hand end of the tube 34 as viewed in Figure 2A is a rejection vane 38 pivoted at 4'0 and arranged to be flipped between the full and construction line positions illustrated by means of alink connection. 42 to the. armature of a loud speaker motor generally indicated at 44. The vane 38 is made as light as possible, for example, being provided with drilled openings to remove excess. material. If a peanut is acceptable the vane 38 will occupy the full line position. and the peanut will pass directly between the Walls 46 and. 48 to a chute 49 which delivers the good peanuts to areceiving receptacle. On the other hand, if a peanut is bad the vane 38 will occupy the construction line position atthe time of its passage and will be deflected into the chamber 50- at the upper end of a rejection chute 5-2 which will deliver the bad peanuts toa suitable receptacle.

Reference may now be made particularly to Figures 4 and; 5 illustrating the photoelectric scanning or viewing systems A pair of plates 54 are spaced from each other by fillers: 56: which provide open! channels for the passage of light beams, one: of these channels being indicated at In openings in each of three positions through the plates 54 there are located combined filter I and diffuser elements in the form of circular inserts 58 of glass or plastic. These are translucent so as to diffuse light and are desirably suitably colored. For example, these may be blue. A lamp 60 is located in each of these filter and diffuser units being provided with an adjustable socket 62 so that suitably colored light, for example blue light, is emitted to the gap between the tubes 34 and 34". Each filter-diffuser is viewable through the gap between the tubes and the passage 64 by a photocell arrangement hereafter described. Pairs of lamps indicated at 70 are carried by plates 68 which are simultaneously adjustable toward or away from the plates 54 by means of screws 66 threaded into nuts carried by the plates 68. Springs 72 are provided to hold the movable plates in adjusted positions. As will be evident from Figures 4 and each pair of lamps 70 is in position to illuminate the surface of a peanut which is toward the photocells at the time the peanut occults the illumination furnished at the corresponding filter-diffuser 58. As will be noted from Figure 4 a triple arrangement is provided so that each peanut is viewed from three sides with the result that substantially its entire surface is subject to viewing. Three lighttight boxes 82 are arranged in a triangular formation opening only to the respective passages 64. In each of these boxes there is an angularly arranged filter 74, for example of blue color, through which illumination may pass to a multiplier photocell indicated at 76. Some of the light impinging on each filter 74, however, will be reflected at right angles through a second filter 78 upon an ordinary photocell 80. The filters 78 may be red filters. It may, at this point, be noted that the colors for the various filters which have been described are arbitrary to the extent that they may be quite different for different objects being viewed. Furthermore, in certain cases the photocells 80 may not be used at all, there being then made suitable circuit modifications as will be evident from the circuit hereafter described. In the case of roasted peanuts, for example, the defects which should cause rejection are usually in the nature of dark spots appearing on an otherwise normally colored surface. In such case it may be solely the dark spots which must be detected. Consistent with this it is only necessary to make initial adjustments such that the light reaching the multiplier photocell 76 through suitable filters in the absence of a peanut will be of substantially the same intensity as the light which reaches the photocell when a good unspotted peanut passes the region between the plates 54. In this case it may be unnecessary to use the photocells 80, a reduction in the intensity on the multiplier photocells effecting the requisite rejection action. On the other hand, as in the case of coffee beans, the rejectability of a bean may be due to a difference in color of the bean as a whole. In such a case it is the ratio of reflectivity of blue light as compared with red light or green light as compared with red light which determines the satisfactory nature of the bean. In this case the two photocells are desirably used in pairs in each of the three sets with suitable filters so that a change of ratio of different light components of the illumination will determine whether rejection is or is not to occur. In still other cases either spots or deviations of color from normal may determine rejectability. Here also suitable filters may be chosen varying, of course, with the different objects which are to be sorted. It will be evident that merely by changes of filters the apparatus illustrated may be applied to a great variety of articles and, of course, dimensions may be changed to sort such articles as large fruits or the like.

The tubes 34 and 34" heretofore mentioned may constitute one continuous tube but desirably, particularly as indicated in Figure 5, they are spaced to provide a viewing gap so as to avoid, to as great an extent as possible, the accumulation of oil or dirt on those portions of the tubes through which light passes. In order to further minimize the accumulation of oil or dirt it is desirable to introduce a flow of air about the open end of the tube 34' by introducing compressed air into the lamp housing 71 through a tube '73. The air flowing about the open end of the tube 34 will then tend to centralize the articles for high speed sorting of objects which are presented for view not only while travelling at high speeds but also when presented in rapid sequence. To accomplish this there is provided the electrical circuit arrangement illustrated in Figure 6.

Before proceeding with the description of the circuit the requirements of the circuit may be mentioned. When an object passes the viewing zone moving at high speed in the projecting air stream it will be evident that the rejecting vane must be capable of moving to rejecting position sufficiently rapidly in response to a rejection signal as to engage the bean before it passes the vane. At the maximum speed of travel the vane may actually be moving at the time the object reaches it so that it, in effect, bats the object into the rejection chamber. On the other hand, it must remain in the rejecting position sufficiently long so as not to move out of the way of an object which is moving at minimum speed and should be rejected. This requires that the vane should have a high rapidity of movement to rejecting position in response to a rejecting signal and should remain there for a short interval sufficient to insure rejection of an object which is moving slowly.

Additionally, however, the vane must be restored to its normal non-rejecting position with great rapidity following its period of rest in rejecting position so as not to reject a good bean which follows closely a bean which has been rejected. It will be evident that high speed of operation in the sense of the number of beans which may be sorted per unit time interval depends upon a proper correlation of these factors. Roughly stated, the apparatus is capable of sorting objects which follow each other at space intervals approximately corresponding to the spacing between the viewing zone and the position of the rejecting vane. It has been found that with the apparatus disclosed sorting may be effected at the rate of upwards of sixty objects per second.

Figure 6 diagrams the connections of the three multiplier photocells 76 which are paired with the photocells 80. A power supply generally indicated at 84, including a conventional filter, has a positive output lead 86 and a negative output lead 88. The positive lead 86 connects to the anode of a regulating pentode 90 which has a resistor 92 connected to its cathode and to a lead 94. A filter condenser 96 connects the leads 94 and 98. The control grid of the pentode 90 is grounded and is connected to the lead 94 through a resistor 98 shunted by a condenser 99. A battery 101 provides a constant screen potential for the tube 90 above the lead 94. A tapped resistor arrangement 100, including a potentiometer having a contact 102 and a fixed resistor 104, is associated with each of the multiplier phototubes and is connected between the line 88 and the line 94. By this arrangement suitable potentials are applied to the dynodes while the cathode potentials of the phototubes may be adjusted by adjustment of the potentiometer contacts 102. The anodes of the multiplier phototubes are joined to the line 94 through the resistor 98 and individual resistors 106, which latter are shunted by adjustable condensers 108.

Between ground and the positive potential lead 114 are connected potentiometers 112, the movable contacts of which are joined to the anodes of the phototubes 80, the cathodes of these tubes being connected to the respective anodes of the associated multiplier phototubes 76.

Three regulating tubes of the conventional gas-filled type are connected in series as indicated at 116, 118 and 120. The connection 114 is joined to the cathode of tube 116 and anode of tube 118. The cathode of tube 118 and the anode of tube 120 are grounded. A second power supply 122 comprising a transformer secondary and full wave rectifier tube has its negative lead connected at 132 to ground and its positive lead 124 connected through a filter 126, line 128 and adjustable resistor 130 to the anode of the tube 116. An additional rectifier tube 134 is connected as illustrated in conjunction with a filter condenser 138 and variable resistance 136 joined to the cathode of the tube 120 to provide a biasing potential across a potentiometer 140.

A set of three gas-filled thyratrons is provided at 142. The anodes of these thyratrons are connected in parallel through resistor 144 to the anode of tube 116. The control grids of these thyratrons are connected through current limiting resistors 146 to the respective junction points of the cathodes of phototubes 80 and anodes of phototubes 76. The cathodes -and suppressor grids of the thyratrons are grounded. A condenser 150 is connected between the anodes of the thyratrons and ground. The anodes are also connected through condenser 152 to the control grid of a triode 154 with which is associated a triode 156. These triodes may be, but are not necessarily, in the same envelope. The anodes of these triodes are provided with load resistors 158 and 160 joining them to the anode of regulating tube 116. Their cathodes are joined together and connected through a common cathode resistor 162 to ground. The grid of the triode 154 is connected to the cathodes of the triodes through a fixed resistor 164 and an adjustable resistor 166. The control grid of the triode 156 is connected directly through the lead 168 to ground. A condenser 17% is connected between the anode of the triode 156 and the control grid of the triode 154.

The anodes of the triodes 154 and 156 are respectively respect to the cathode of this tube by reason of the cath-' ode resistor 180. Screen potential for the pentodes 176 and 178 is provided through resistor 186 from the line 128, the screen grids being connected to the cathodes through a condenser 188.

The anode of the pentode 176 connects with one end of the driving coil 190 of the loudspeaker motor 44 while the anode of the pentode 178 connects to one end of the second driving coil 192 of this motor. The other ends of these coils are joined to the line 194 and through the field coil 196 to the positive supply line 124. The armature of the motor 44 which extends through the coils 190 and 192 is indicated at 198 while the field core 2% is energized by the field coil 196 with the result that the armature 198 will be flipped between two alternative positions as one or the other of the pentodes 176 and 178 carries a greater current, the coils 190 and 192 being wound and connected in the circuit to effect this result. The armature 198, as previously described, is connected to the rejecting vane 38, the moving parts all being light and capable of great rapidity of movement between their alternative positions under the actions of quite large currents through the power pentodes. A spring 199 is desirably provided biasing armature 198 towards rejecting position so as to increase the rate of movement of the rejecting vane to rejecting position.

It will be understood that the heater supplies for the various tubes, which are not illustrated, are conventional. I

The operation of the electrical circuit may now be described. In the absence of an object to be sorted the multiplier phototubes 76 will have a maximum conductivity and hence will draw current through the resistors 106 which, as will be seen from the diagram, are so arranged in the circuit that the control grids of the thyratrons 142 will be negative with respect to their cathodes and hence will prevent firing. At this time substantially all of the illumination of the tubes 80 is prevented by reason of the fact that the light from the lamps is filtered by the filters 58 so that the portion reflected by the filters 74 will be cut off by the contrasting filters 78. The result is that the thyratron control grids will not receive any appreciable positive control potential by virtue of currents through the phototubes 80.

v The condenser 150 will be charged through the resistor 144 from the positive potential which exists at the anode of regulating tube 116. As to the triodes 154 and 156, the former will be conducting and the latter non-conducting. This is due to the fact that understatic conditions the control grid of the triode 154 is at its cathode potential due to direct connection with the cathode through the resistances 164 and 166 which are not conducting current. The cathode current from the tube 154 passing through the resistor 162 renders the control grid of the triode 156 highly negative with respect to its cathode so that this tube is normally cut ofi.

Again considering static conditions, the adjustment of the contact of potentiometer 140 is so made that the tube 178 conducts a current considerably in excess of the current conducted by the tube 176. The result is that current flows in the coil 192 causing the armature 198 and the vane 38 to occupy the position corresponding to acceptance of an article undergoing sorting. This is desirably the static condition since, of course, it is to be expected that more articles will be accepted than will be rejected.

if now there passes within the field of view of the photocells an article which is acceptable substantially no change should occur in the system since the reflection of light from the article should affect the multiplier photocells 76 to the same extent as the light previously emanating from the lamps 60. Furthermore, the light reflected from an acceptable article should not cause any appreciable illumination of the photocells 80, at any rate, to the extent of causing them to raise the control grid potentials of the thyratrons to the firing points. The result would be, therefore, no disturbance of the circuit and the vane 38 would remain in its normal position On the other hand, let it be assumed that there passes through the field of vision of the photocells an article which should be rejected. If the rejection is merely by reason of diminution of the light reaching one of the multiplier phototubes due, for example, to dark spots, the diminution of multiplier phototube current through a resistor 106 will cause a rise of potential of the control grid of the corresponding thyratron causing the thyratron to fire by reason of the discharge of condenser therethrough. This discharge will be only momentary and the tubes will then deionize since the resistance 144 is chosen sufliciently high to prevent continuous ionization. By the time condenser 159 is recharged through the resistance 144 the article will have passed the phototubes and consequently the control grid of the fired thyratron will have been restored to its normal negative potential.

Firing of a thyratron may also occur if an increase of illumination occurs on the cathode of an associated phototube 80 even Without diminution of the illumination on the corresponding phototube 76. An increase of current through a tube 80 from the line 114 will raise the potential at its cathode, so raising the grid potential of the associated thyratron.

Furthermore, there may be, concurrently, increase of illumination of a phototube 80 and decrease of illumination of the associated phototube 76 by reason of change in color balance as, for example, in the sorting of cofiee beans. This, of course, will also result in the firing of one of the thyratrons.

It will be evident that the firing may be produced in a variety of ways depending upon the articles being sorted and the color or shade difierences between good and bad articles. The filters 58, 74 and 78 may be correspondingly chosen. With such choices it will be seen that the apparatus may be employed for sorting a quite unlimited range of articles. In the event illumination on the phototubes 80 is not required for rejection action these may be either cut out of the circuit entirely, with elimination of those circuit elements which thereby become unnecessary, or for the phototubes there may be temporarily substituted fixed resistors which, for the sorting of some other articles, may then be replaced by phototubes.

The firing of any one of the thyratrons in any one of the fashions just indicated will cause a negative pulse to be transmitted to the control grid of triode 154 through the condenser 152. The result of this will be the cutting off of triode 154, and by virtue of this cut ofi, current flow will take place through triode 156.. A positive pulse will accordingly be emitted from the anode of the triode 154 and a negative pulse will be emitted from the anode of the triode 156. The latter pulse, it will be noted, will be applied through the condenser to the'control grid of the triode 154 driving it even further in the cut off direction. Restoration of the normal conditions of the triodes will then take place only after an interval involving recharging of the condensers flirough the resistances 164 and 166. This restoration involves the attainment of conductivity of triode 154 and of cut 011 of triode 156 with resulting emission of reverse pulses from the anodes of these triodes. There is thus provided a pulsing in one direction followed after a predetermined interval, adjusted by adjustment of resistance 166, by a pulsing in the op posite sense.

The initial positive pulse emitted from the anode of triode 154 will render the power pentode 176 conductive and, at the same time, will drive the power pentode 178 toward cut off by increasing the current flow through the cathode resistor 180. The result is that current Wlll flow through the driving coil 190 and will be greatly reduced or cut off through the driving coil 192 so that the armature 198 and vane 38 will be driven toward rejecting position. Following this by an interval corresponding to the restoration of the triodes 154 and 15 6 to their normal conditions the pentode 178 will again become conductive and the pentode 176 will again become non-conductive, in a relative sense, causing the armature 198 to be restored to its normal position. By using relatively large condensers at 172 and 174 and relatively high resistances at 182 and 184 the tubes 176 and 178 are caused to retain their pulsed conditions for rejection until restored to their static conditions.

The interval referred to may be set, as described above, so as to correspond to that time interval which may exist between the time of arrival of an article moving at high speed and the time of arrival at an article moving at low speed at the position of the rejecting vane, i. e., the vane will move to its rejecting position sufficiently rapidly to reject the fastest moving article and will remain there sufficiently long to reject a slowly moving article.

There may now be described certain matters of the circuit which involve refinements of operation. It sometimes occurs that the presence of minor spots on articles such as peanuts should not lead to their rejection. The sensitivity of the system in this respect may be adjusted by adjustment of the condensers 108 which will serve to bypass signals due to reduction of illuminations of short duration such as might occur due to small spots of discoloration. The circuit may be adjusted by these condensers so as to be more or less critical as to acceptability of the articles being sorted.

For satisfactory operation of the multiplier phototubes fine control of the potentials of their elements is required and one function of the pentode 90 is to secure automatic control of the potential applied to these elements. However, the tube 90 has an additional function. This may be best exemplified by considering the situation presented in the sorting of peanuts which have been roasted. When glass guide tubes such as 34' and 34" are used, and it is generally desirable to use such a tube rather than to project the articles merely through a large air gap without guidance, the tubes will gradually accumulate interior coatings of oil reducing illumination. By the provision of the resistance 98 and condenser 99 and by reason of the fact that current to the anodes of the phototubes 76 passes through this resistance the pentode 90 automatically adjusts the potential conditions so that a gradual deterioration of intensity of illumination will not affect the selection. The condenser 99 produces only a gradual readjustment of this type and avoids reduction of sensitivity to those transient reductions of illumination which should and will effect rejection.

Figures 7 and 8 show a modified form of feeder which may be used in place of the pneumatic feeder heretofore described. In this arrangement the articles to be sorted are fed by a pair of belts. Upper pulleys 202 and lower pulleys 204, one set of which may be driven at a suitable speed, support the belts 206 faced with sponge rubber or similar soft material indicated at 203. The sponge rubber laps of the two belts are in contact with each other as indicated in Figure 8 so as to grip the articles being sorted, delivered from a chute 210 which may have a V cross-section as described above in order to align the articles in single file in contact with each other. As will be evident, if the belts are moved at a suitable linear speed the articles dropping from the end of the chute 210 will be approximately uniformly spaced and in single file with a minimum spacing amounting to substantial contact of the successive articles. The belts should be operated at such a speed that if the articles are in contact the frequency of their passing a given point is the frequency desired for presentation of the articles to the scanning system. A funnel indicated at 212 will serve to align the articles so that they will drop from the funnel through substantially the same path past the scanning zone in the scanning device 214 which may be identical with that previously described. If desired, the articles may drop through the air or may drop through one or more transparent glass tubes such as previously described. Suitably spaced from the scanning system is the rejecting vane 216 which, when occupying a normal position indicated in full lines, will permit the articles to drop into the accepting chute 218 Whereas if it is 1n the construction line position the articles will be deflected into the rejection chute 220.

While the articles fed by the belts as aforesaid Wlll pass any given point in their path at a substantially constant frequency their free drop under the action of grav ty will cause them to become linearly spaced and the distance between the scanning system and the rejecting vane will, therefore, be so chosen that they will have the proper linear spacing to permit the vane to flip to a rejecting position in response to a re ection signal before the article to be rejected may reach the position of the vane. The electrical system involved may be identical to that previously described and should be ad usted to secure the same characteristics of operation, i. e., the vane, when it moves to rejecting position, should llnger in such position sufficiently long to reject a possibly slowly moving article but should return to accepting positlon before a subsequent article may arrive thereat. This apparatus, however, by reason of utilization of gravity to accelerate the articles results in the attainment of more uniformity of speed of movement than can be obtained by the pneumatic system heretofore described.

It will be evident from the foregoing that various aspects of the invention may be useful without association with others: for example, the circuit arrangement may be used for the selection of articles which are supported on a conveyor rather than being subject to free motion in air. It will, of course, also be evident that various circuits may be provided suitable for effecting sorting and also that the scanning system employed is subject to considerable variation. Illumination may be by ultraviolet or infra red radiation rather than by visible radiation so that reflecting, or fluorescent, properties of the articles under such illumination may be utilized for selection. It will also be clear that the multiplier and ordinary phototubes may be interchanged or that the circuit connections may be reversed so that firing would occur upon increase rather than decrease of the current through the tubes occupying the positions of the multiplier phototubes above described.

While the apparatus has been specifically described as efiecting the actual segregation of acceptable from unacceptable objects it will be apparent that the sorting action may involve merely indication of quality without actually segregating dilferent classes of objects; in other words, the apparatus may be used for purposes of inspection or control.

In the case of inspection, for example, to give a fair indication of the quality of a batch of objects the outputs from the tubes 176 and 178 may control counters in such fashion that one counter would count those objects of less than some predetermined quality and the other would count those of more than the predetermined quality. The ratio of these counts would then be indicative of the average quality of the batch. Other alternatives will be readily apparent; for example, only one of the tubes might control a counter with the total number of objects passing being counted in conventional fashion 2y an additional and independent photoelectric counting evice.

The apparatus is also suitable for effecting control. For example, if beans or nuts are roasted they may pass from a continuous roasting apparatus through the sorting apparatus which, by a counter arrangement such as described, will accumulate continuously the ratio of improperly roasted to properly roasted beans or nuts. This ratio may then control the temperature of roasting or the rate at which the materials pass through the roaster so as to afford a continuous control on the roasting operation. In view of such uses of the apparatus it will be understood that the term sorting, unless limitations to the contrary are found, is to be construed as referring to differentiation of objects of different qualities even though actual acceptance or rejection is not effected. The invention is not to be regarded as restricted except as required by the following claims.

What I claim and desire to protect by Letters Patent is:

l. Photoelectric sorting apparatus including a common supply container for articles to be sorted, a plurality of passages for said articles, means for feeding the articles from said container and distributing them to said passages, means for selecting articles one by one from said passages in succession and for projecting th em 1n an elastic fluid stream singly through a single viewing zone, means for illuminating the articles during passage through said viewing zone, photoelectric means for viewing the articles during passage through said viewing zone, and means responsive to said photoelectric means for effecting selective acceptance or rejection of said articles.

2. Photoelectric sorting apparatus including means for effecting movement of articles to be sorted along a path including a viewing zone providing visibility of the entire surface of each article during its passage through said viewing zone, means for illuminating the articles during passage through said viewing zone, a plurality of photoelectric means arranged to view simultaneously substantially all portions of the surface of an article during movement through said viewing zone, each of said photoelectric means including a pair of differentially connected phototubes positioned to receive light reflected from an article in said viewing zone and a thyratron having a control grid, said pair of phototubes being connected to said control grid and controlling the firing of the thyratron, and means responsive to firing of the thyratron by said phototubes for actuating selecting means for effecting selection of said articles.

3. Photoelectric sorting apparatus including means for effecting movement of articles to be sorted along a path providing visibility of the entire surface of each article, means for illuminating the articles during passage through said viewing zone, a plurality of photoelectric means arranged to viewv simultaneously substantially all portions of the surface of an article during movement along said path, each of said photoelectric means including a pair of differentially acting phototubes, a thyratron arranged to receive differential electrical signals from its pair of phototubes and subject to firing by such signals, and masking means confining the region of view of an article by the phototubes to a region which is relatively narrow in the direction of movement of the article, and means responsive to said photoelectric means for effecting selective acceptance or rejection of said articles.

4. Photoelectric sorting apparatus including means for effecting movement of articles to be sorted along a path providing visibility of the entire surface of each article, a plurality of photoelectric means arranged to view simultaneously substantially all surfaces of an article during its passage along said path, means for illuminating the surface of an article exposed to each of said photoelectric means during its passage along said path, illuminating means in addition to the first mentioned illuminating means providing a background for each surface of the article exposed to a photoelectric viewing means during the passage of the article along said path, and means responsive to said photoelectric means for effecting selective acceptance or rejection of said articles.

5. Photoelectric sorting apparatus including means for efiecting movement of articles to be sorted along a path providing visibility of the entire surface of each article, a plurality of photoelectric means arranged to view simultaneously substantially all surfaces of an article during its passage along said path, means for illuminating the surface of an article exposed to each of said photoelectric means during its passage along said path, illuminating means in addition to the first mentioned illuminating means providing a background for each surface of the article exposed to a photoelectric viewing means during the passage of the article along said path, said backgrounds presenting to said photoelectric means substantially the same appearance, with respect to the response characteristic of said photoelectric means, as an acceptable article, and means responsive to said photoelectric means for effecting selective acceptance or rejection of said articles.

6. Photoelectric sorting apparatus including means for effecting movement of articles to be sorted through a viewing zone, means for illuminating the articles during passage through said viewing zone, photoelectric means for viewing the articles during passage through said viewing zone, said photoelectric means including a pair of phototubes viewing simultaneously substantially the same area of each article in said viewing zone, arranged to have different color responses and connected to provide a differential response, said photoelectric means also including a thyratron having a control grid, said pair of phototubes being connected to said control grid and controlling the firing of the thyratron, and means responsive to firing of the thyratron by said phototubes for actuatiiig selecting means for effecting selection of said artic es.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 279,034 Smith June 5, 1883 1,874,069 Weigl Aug. 30, 1932 1,945,395 Cockrell Jan. 30, 1934 2,008,410 Wilson July 16, 1935 2,122,769 Bergmann July 5, 1938 2,183,606 Day Dec. 10, 1939 2,190,935 Cox Feb. 20, 1940 2,228,559 Cox Jan. 14, 1941 2,244,826 Cox June 10, 1941 2,314,063 Anderson Mar. 16, 1943 2,345,967 Gent Apr. 4, 1944 FOREIGN PATENTS Number Country Date 294,575 Great Britain July 20, 1928 492,035 Great Britain Sept. 14, 1938 

